/*
 * Copyright (c) 2011 Imre Fazekas.
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of the Brillien nor the names of its
 * terms and concepts may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package com.vii.streamline.services.script;

import com.vii.streamline.services.error.StreamLineException;
import sun.org.mozilla.javascript.internal.Function;
import sun.org.mozilla.javascript.internal.Scriptable;

import javax.script.*;

/**
 * Utility class dealing with Javascript codes
 */
public class ScriptServices {

    private static ScriptEngineManager seManager;

    static{
        seManager = new ScriptEngineManager();
    }

    /**
     * Creates a new Scripting engine instance
     */
    public static ScriptEngine createScriptEngine() {
        return seManager.getEngineByName("JavaScript");
    }

    /**
     * Creates a new ScriptContext from the given ScriptEngine instance
     */
    public static ScriptContext createScriptContext( ScriptEngine jScriptEngine ) {
        return jScriptEngine.getContext(  );
    }

    /**
     * Evaluate the given string containing a script code
     * @param jScriptEngine actual ScriptEngine
     * @param jScriptScriptContext actual ScriptContext
     * @param s script code
     * @param <T> generic type of the result
     * @return result of the execution of the script
     * @throws StreamLineException any case of error
     */
    public static <T> T eval( ScriptEngine jScriptEngine, ScriptContext jScriptScriptContext, String s ) throws StreamLineException {
        try {
            return (T) jScriptEngine.eval( s, jScriptScriptContext );
        } catch (ScriptException e) {
            throw new StreamLineException( e );
        }
    }

    /**
     * Calls a function defined in a previously evaluated javascript.
     * @param jScriptEngine actual ScriptEngine
     * @param jScriptScriptContext actual ScriptContext
     * @param methodName name of the function
     * @param parameters parameters to the function
     * @param <T> generic type of the result
     * @return result of the call
     * @throws StreamLineException any case of error
     */
    public static <T> T call( ScriptEngine jScriptEngine, ScriptContext jScriptScriptContext, String methodName, Object... parameters ) throws StreamLineException {
        Object f = jScriptScriptContext.getAttribute( methodName );
        if( f == null || f == Scriptable.NOT_FOUND || !(f instanceof Function) )
            throw new StreamLineException( "Method not found!" );
        Function ff = (Function)f;

        Invocable inv = (Invocable) jScriptEngine;
        try {
            return (T)inv.invokeFunction( methodName, parameters );
        } catch (Exception e) {
            throw new StreamLineException( e );
        }
    }

}
